DE2722422A1 - Internal combustion engine exhaust system and silencer - uses tubes with multiple bores to cool exhaust gas - Google Patents

Abstract

A silencer forming part of the exhaust system of an internal combustion engine consists of two concentric tubes (51, 52). These tubes are joined by radial walls (55) which extend longitudinally so that the annular space between the tubes is divided into a number of separate compartments (5). A cooling fluid flows in these compartments (5) in the opposite direction to the flow of gas in the central bore (50). The outer wall of the outer tube (52) has a number of radial fins (56) which also extend longitudinally. These fins help to dissipate the heat which has been transferred to the cooling medium by convection and radiation.

Description

Additional registration to P 22 21 167.2 (afterburning chamber wall ").

Designation: Thermal gas flow in the combination of ceramics / metals Afterburners.

Description With the Ilauptanmeldung P 22 21 167.2 is for Kanstruktion A composite system ceramic / metal has been submitted for afterburning chamber walls. It was the task of this construction, by covering the ceramic afterburner inner wall with metal for the cold start phase, the heat loss from the first reactions into the smallest possible Limit reactor mass. The means for this was the arrangement of stainless steel sheet in such a way that there is practically no heat exchange during the cold start phase of importance from the metal surface beyond the combustion chamber into the Pottery can go on. It is the job of this supplementary registration, while maintaining the favorable initial start situation at the same time to integrate measures, which the fast Limit heat build-up when the desired temperature level (around 800 E) has been reached is. Two groups of measures are presented for this purpose. The first group uses provided in the main application claim 2 between ceramic and metal wall Gap in such a way that a kind of short-circuit path for heat dissipation from the hot core the afterburning chamber is achieved directly in the outlet zones of the device. The second Group secures a heat dissipation path from the outer wall of the ceramic wall part.

The accompanying FIG. 1 shows the overall system of an afterburning device directly to the engine outlet or (in the case of multi-cylinder engines) to the manifold Connected line 44 discharges the exhaust gas into a relaxation space 45 from which it passes through the perforations 41 into the annular space 28. This room 28 is with his Wall 46 in the heat exchange to afterburner exhaust gas, which is straight through the perforated screen 33 has left the combustion chamber, and with its wall 42 in heat exchange with afterburner exhaust gas, through heat dissipation to the additional air inlet sections 34, 35 and 36 has already become cooler. In this way as it moves through space 28 thermally enriched engine output is then used as the driving medium for the The additional air injector is released into the tubes 29 and thus into the combustion chamber. The reverse flush wall 54 is designed as "surface radio function" according to claims 3 and 4 of the main application.

From the partial section of Figure 2 it can be seen how the gap formation takes place between the metal layer (2) and the ceramic wall part (4): elongated ones are created Gas guide channels 21 which are covered in Figure 1 by the ceramic wall. she have unilateral openings 48, which face the outlet plenum 51, thereby there is a constant radiation of heat from the spaces 21 in the outlet zone, the Zones through which the hot afterburner exhaust gas passes behind the combustion chamber (30, 38, 26 and 24), thermally relieving. This thermal relief can thereby be increased that the afterburner exhaust gas flowing into the ceramic part through the perforations 25 is not only transferred into the partial flow channels 24, but already immediately from the zone of the perforations 25 into the (in Figure 1 hidden behind the ceramic wall 4) inner partial flow channels 21, through whose outlet openings 48 it is in the outlet plenum 51 arrives in the same way as that gas that the partial flow group 24 happened. The inlet into the partial flow group 21 is shown in the construction figure 1 easy to achieve in that the ceramic cylinder on the end wall of the Space 28 is not flush, but rests with a space (and spacers).

The second heat dissipation path is that the outer wall of the ceramic afterburner jacket (4) constantly from already cooled down afterburner exhaust gas is rinsed. Its surface is due to ribbing and the resulting Channel bed groups 24 enlarged. The cover is made by metal studs 23, If possible, made of material with high thermal conductivity such as aluminum and for heat dissipation Provide with material accumulations such as external ribs if possible. Besonaers is suitable a drilling chamber cooling pipe as described in claims 8, 11 and 12 of application P 27 18 944.2 of the same applicant is described. As the Figure 2 the designated application represents it in detail, are in this Kohlkammer tube, which is primarily made of aluminum, cavity ribs provided with their inlet and outlet openings facing the free atmosphere. The construction principle according to this corresponds essentially to the figure 3 of the additional application, to be presented is that the inner wall 49 there then coincide with the wall 23 in FIG would. The partial flow guide channels 58 serving as air throughput cooling sections would have then (in a flatter design) on the inlet and outlet side access to the free atmosphere or would be replaced by another heat-dissipating medium (inclusion in a cooling circuit) flowed through. With a different overall design, the intake of engine exhaust gas, especially if it is still untreated and subjected to a special grinding process through channels 24. With a multi-ring hollow-chamber cooling tube several such possibilities can also be combined, as described in the application P 27 18 944.2 of the same applicant is described.

The sum of these measures is up to the designer of an afterburning device a broad voting system is available that allows it to be economically viable To create compact systems with which the thermal load on the afterburning gas can be controlled without the conditions that are required in a combustion chamber for rapid Cold start and then for thermal level limitation must be observed, be affected. Above all, it is only possible with this "middle package" that exhaust gas adjustment on the engine side (e.g. the lambda value of the carburetor setting) to regulate the leanest charge value of the afterburning plant so that even with thermoreactors without increasing fuel consumption.

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Claims (8)

Claims S Nachbrennraunwandung according to P 22 21 167.2 claim 2 with a space between the inner metal layer and the surrounding xeramik part, characterized in that the gas exchange in this interspace by what is still untreated There is engine exhaust, which is located in the feed line to the afterburning chamber, or by such treated engine exhaust gas that has already passed through the afterburning chamber but also had to pass at least one ice lane zone. 2. Nachbrennraumwandung according to the previous claim, characterized in that that the ceramic component has elongated indentations (21) and the metal wall partially rests on rib-like bulges (2 in Figure 2). 3. Nachbrennraumwandung according to one of the preceding claims thereby characterized in that the elongated space is only provided with a thermal radiation opening (48 in Figure 1) is provided for each partial flow or for the entire annulus, which faces an outlet plenum (51). 4. Nachbrennraumwandung according to the previous claims 1 and 2 thereby characterized in that the elongated space for each partial flow or for his entire ring-like flow space each having an inlet and outlet opening. 5. Nachbrennraumwandung according to the previous claim, characterized in that that not only the inner ceramic wall elongated flow spaces in the composite forms with a form-fitting partially abutting metal wall, but also the outer one geramikwandung (21 and 24 in Figures 1 and 2). 6. Nachbrennraumwandung according to the previous claim, characterized in that that the outer metal wall (23 in Figures 1 and 2) as a simple cylindrical Jacket or additionally designed with external ribbing or as a hollow chamber annulus is. 7. Nachbrennraumwandung according to one of the preceding claims characterized in that the inner wall made of stainless steel (2 in Figure 1 and 2), which with the inlet sections for exhaust gas and additional air form a stable molded body represents, in their cylindrical or profiled longitudinal extension at the same time as Assembly guide rail for the ceramic wall part to be introduced and the adjacent one Metal wall outer part (23) or exhaust gas inlet or downstream sections attached to it serves. 8. Nachbrennraumwandung according to one of the preceding claims thereby characterized in that the outer metal wall (23) with an exhaust gas collection chamber (51) and the adjoining cooling section (49/59/58) forms a uniform structure, which is made entirely of aluminum and flows into the open atmosphere,